The present invention relates generally to a backhoe forming a part of a machine commonly referred to as a tractor-loader-backhoe and, more particularly, to a decelerator for the hydraulic cylinder operably vertically moving the backhoe boom assembly.
In the operation of backhoes, the complete retraction of the boom cylinder to effect a raising of the boom assembly into an elevated transport position causes a shock loading to the boom cylinder due to the mass of the boom assembly being elevated and a bottoming out of the boom cylinder. To minimize damage to the boom cylinder, to reduce impact stress on the structural components of the machine, and to increase operator comfort by reducing vibration and shocks induced throughout the machine during operation thereof, it has been found desirable to provide a decelerator in the boom cylinder to slow the flow of hydraulic fluid from the boom cylinder as the boom cylinder nears the completely retracted position. By decreasing the flow rate of the hydraulic fluid from the boom cylinder immediately prior to being retracted completely, the speed of the collapsing cylinder is slowed and the shock to the cylinder is reduced.
Known prior art decelerators have typically used a taper on the retraction end of the piston that would restrict the exhaust of hydraulic fluid out of the exhaust port. Because of a need to increase machining tolerances on both the assembly of the barrel of the boom cylinder and of the piston taper comprising the prior art decelerator, known prior art decelerators did would not always be able to function properly. Accordingly, it would be desirable to provide an improved boom cylinder decelerator that would not be dependent upon the maintenance of tight manufacturing tolerances for proper operation.